Sigfox Sens'it User manual

Sens’it antenna
Implementation rules & Integration
guideline

1Sens’it antenna overview
2Antenna Performance overview on Sens’it device
3Integration guidelines
4Antenna tuning and matching parameters

Sens’it antenna
overview
The Sens’it antenna is made of two parts:
•A metal part
•A PCB printed part
This is a folded PIFA - like antenna.
It is possible to implement this antenna in
other devices, however, some precaution
must be taken
In most cases, only the printed part should
be modified in order to implement this
antenna in another device.
This document describes how to tune
and match the sens’it antenna and
provide recommendations on how to
implement this antenna into another
device.
Sigfox presentation 3

Sens’it radiation
pattern
The Sens’it antenna
provides an omnidirectional
radiation pattern when
implemented in the Sens’it
device.
The radiation pattern is
mainly driven by the size and
form factor of the PCB as
well as the antenna location.
Changing one of those three
parameter can impact the
radiation pattern.
Sigfox presentation 4
•Antenna gain : +1dBi
•Antenna efficiency : -1dB
•ERP = 13dBm (for 14dBm input power)
•EIRP = 23dBm (for 22dBm input power)

Sens’it antenna
Impedance
The sens’it antenna has
enough bandwidth to cover
the whole Sigfox frequency
range.
•Return loss below -8dB
over whole Sigfox
frequency range.
•Reference impedance
50Ohms
Sigfox presentation 5
-8
Measured Return
Loss plot
Smith Chart

Sensit antenna
Sigfox presentation 6
Parameter impact on
antenna
Parameters
Impact
Comment
Casing ++
•
A casing change will impact the frequency tuning
•
It is better to keep ABS PC type casing
PCB length ++
•
PCB length will impact the frequency tuning as well
as
the antenna Bandwidth
PCB width +++
•
PCB width will impact the frequency tuning as well
as
the antenna Bandwidth
•
It will require a retuning and matching of the antenna
Component location +
•
Changing the electronic is not critical though it
may
require
•
Avoid placing big components next to the antenna
Battery location ++
•
The battery can be changed but an antenna
tuning
may be necessary
•
Try to keep the battery as far as possible from
the
antenna and avoid long wire to connect it to the PCB
+
++
+++
Limited impact
Moderate impact
High Impact

Sens’it area
To avoid antenna retuning
and matching, respect the
different component areas.
Low profile component include CMS
chicken food components (eg.
capacitors, coils, resistor)
Sigfox presentation 7
All component allowed
Low profile components allowed
No components allowed
All component allowed
Low profile components allowed
No components allowed
Back side Front side
Front side
Back side

Antenna tuning
and matching
parameters
Sigfox presentation 8
Frequency tuning
The size of slotA can be modified to tune
the resonance frequency of the antenna
•Slot A length increase Fc move
down
•Slot A length decrease Fc move up
Antenna Matching
Adjusting the dimension B will impact the
antenna matching (impedance of the
antenna)
A
B
As any antenna, the sens’it antenna uses the PCB to operate and is
impacted by its surrounding (e.g. casing…)
Therefore, implementing the sens’it antenna in your device can require
some tuning and matching in order to optimize the antenna
performance.
This optimization can be done by adjusting two parameters of the PCB
printed part of the antenna.

Thank you!